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Toyota Corolla Repair Manual: Circuit description

When a misfire occurs in the engine, hydrocarbons (hc) enter the exhaust in high concentrations. If this hc concentration is high enough, there could be an increase in exhaust emissions levels. High concentrations of hc passing through the catalyst also cause to temperature of the catalyst to increase, possibly damaging the catalyst. To prevent this increase in the emissions and limit the possibility of thermal damage, the ecm monitors the misfire rate. When the temperature of the catalyst reaches a point of thermal degradation, the ecm will blink the mil. For monitoring misfire, the ecm uses both the camshaft position sensor and crankshaft position sensor. The camshaft position sensor is used to identify misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter increments when crankshaft rotation speed variations exceed threshold values.

The ecm illuminates the mil if the misfiring rate exceeds a threshold value and could cause emissions deterioration.

Hint:

Hint

: when codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indicates that the misfires have been detected and recorded at different times.

Reference: inspection using oscilloscope with the engine idling, check the waveform between terminals #10 to #40 and e01 of the ecm connectors.

Hint

: the correct waveform is as shown.

Monitor description

Monitor description

The ecm illuminates the mil if the misfiring rate exceeds a threshold value

The ecm illuminates the mil if the misfiring rate exceeds a threshold value and could cause emissions deterioration.

The ecm will illuminate the mil when the percent misfire exceeds the specified limit per 1,000 engine revolutions.

One occurrence of excessive misfire during engine start will set the mil. Four occurrences are required to set the mil 1,000 revolutions after engine start. (2 Trip detection logic) the mil blinks when percent misfire causing catalyst damage per 200 revolution met 3 times (1 time if the engine rpm is in high speed range). (Mil blinks immediately)

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Wiring diagram

Wiring diagram

Refer to dtc p0351  for the wiring diagram of the ignition system.

Confirmation driving pattern

Random/multiple cylinder misfire detected
Dtc p0300 random/multiple cylinder misfire detected Dtc p0301 cylinder 1 misfire detected Dtc p0302 cylinder 2 misfire detected Dtc p0303 cylinder 3 misfire detected Dtc p0304 cylinder 4 misfire ...

Confirmation driving pattern
Connect the handheld tester or the obd ii scan tool to the dlc3.  record dtcs and the freeze frame data.  set the check mode using the handheld tester .  read the value on th ...

Other materials:

Problem symptoms table
The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to troubleshoot the problem when a normal code is displayed in the diagnostic trouble code chart but the problem is still occurring. Numbers in the table indicate the order in which the circ ...

Inspection
1. Inspect sliding roof limit switch Inspect the sliding roof limit switch continuity. Standard: If the continuity is not as specified, replace the switch. 2. Inspect sliding roof drive gear subassy Connect the positive (+) lead from the battery to terminal 2 and the nega ...

How to proceed with troubleshooting
1 Vehicle brought to workshop 2 Customer problem analysis 3 Check and clear dtcs and freeze frame data 4 Problem symptom confirmation Symptom does not occur: go to step 5 Symptom occurs: go to step 6 5 Symptom simulation 6 Dtc check There is no output: go to step 7 There is outp ...

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